1. Field of the Invention
The present invention relates to arrangement in a riflescope for correcting the ballistic trajectory and, in particular, to an arrangement in which turning of a magnification alteration ring will cause an alteration of the image size of the target, on the one hand, and, at the same time, will effect a shift of the target image within the viewing field including a reticle and scales for the sight in the vertical direction under minute axial tilting adjustment of the erecting lens tube for achieving a virtually corrected line of the sight, on the other hand, whereby adjustment of target aiming is effected automatically with instantaneous indication of the hit point, said riflescope permitting rapid response to every change in the type of bullet used in the rifle by means of a changeover ring incorporated in the arrangement.
2. Description of the Prior Art
Generally, the purpose of a riflescope is to provide for easy aiming with a rifle at distant game, such as a bird or an animal (referred to as the target in the following), by making use of an enlarged view of the target to make visual identification thereof easier.
In aiming at a target using a riflescope, an adjustment of the sight in the vertical as well as in lateral directions, on the one hand, and an in situ correction of the ballistic trajectory, on the other hand, are necessary for hitting the target properly. Since ballistic trajectories of rifle bullets are different depending on the specific distance between the gun and the target (see FIG. 4). In conventional riflescopes, the after-correction of the ballistic trajectory is effected by the shooter by manipulating an adjustment dial arranged on the upper face of the scope tube to adjust it to the scale corresponding to each specific distance to the target which the shooter has estimated beforehand with the aid of the magnification of the target image, so as to shift the sight correspondingly in the vertical direction.
As stated above, conventional arrangements require, after an estimation of the distance has been effected, an after-correction operation for the adjustment dial, so that a time-consuming, annoying two-step operation due to the distance estimation and the dial manipulation is unavoidable. This is a very significant disadvantage for a rifle shot that requires a most prompt correction of the ballistic trajectory.
For solving such a problem, the inventor previously made a proposal in Japanese Utility Model Application Sho 61-173977 for a fully automatic device for correcting the ballistic trajectory. This prior proposal deals, however, with a correction mechanism effective for only one specific type of bullet and is not applicable at all, or is hardly applicable, to different rifles with difference types of bullets.
In relation to the correction of the ballistic trajectory of a gun for various types of bullets (bullets of several sizes, shapes, amounts of gunpowder in the cartridge and so on can be used in the same rifle), various measures may be taken, for example, to exchange the dial for another one having different scale, to neglect the differences in ballistic trajectory for different bullets, to limit the type of bullet to be employed to a one single type, etc.
The present invention attempts to overcome the difficulties in such measures as described above, such as inaccuracy in the sight, inconveniences in operation and so on, and to make possible to attain a simple and easy correction of the ballistic trajectory for various types of bullets by the hands of the shooter, so as to widen the range of utilization of the riflescope.